1. Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to a base station receiver for receiving a closed-loop transmit diversity uplink transmission.
2. Background
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-in-single-out, multiple-in-single-out, single-in-multiple-out, or a multiple-in-multiple-out (MIMO) system.
A transmit diversity system employs multiple transmit antennas and multiple receive antennas for data transmission. A transmit diversity channel formed by the transmit and receive antennas may be decomposed into several independent spatial channels. Each of the independent spatial channels corresponds to a dimension. The transmit diversity system can provide improved performance (e.g., higher throughput and/or greater reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized.
Generally, during uplink communications, two aspects may be observed, with the first being related to transmit power, while the second may be related to interference observed at base station. With respect to the first aspect, an access terminal may be limited by a maximum transmit power and as such a limited maximum correlated data transmission rate. With respect to the second aspect, interference caused by other users may limit system capacity.
As the demand for mobile broadband access continues to increase, research and development continue to advance the UMTS technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.